This invention relates to a device for adjustably mounting a wall covering, such as shim slats or drywall to an uneven wall surface or uneven studs to create a flat surface. An example use for this invention is in the application of bathroom tile, where a flat base surface must be created before the tile can be applied. The invention includes a screw means, provided with an annular plateau perpendicular to the axis of the screw, upon which rests a support means for supporting the wall covering.
Devices are known in the art for adjustably fastening items, such as window and door frames, to fixed elements, e.g., U.S. Pat. No. 4,486,134 and U.S. Pat. No. 4,655,656. By these known devices, a screw is provided with an unthreaded area near the head, around which is positioned a sleeve having external threads for engaging the frame.
U.S. Pat. No. 4,655,656 discloses a combination of a sleeve and a screw where the sleeve is driven into a pre-bored hole in the frame. The screw is then inserted through the sleeve, through the hole and into the fixed element. When the bottom surface of the screw head and the top surface of the sleeve contact, they engage each other, allowing for the screw and the sleeve to be driven clockwise simultaneously. Once the sleeve is flush with the frame, the screw can be rotated counterclockwise without turning the sleeve, allowing for adjustment of the spacing between the frame and the fixed element.
U.S. Pat. No. 4,486,134 discloses a similar arrangement of the screw and sleeve, but has an embodiment where a split spring ring engages a slot in the screw to maintain the screw's axial position with respect to the frame, while allowing rotation and adjustment of the spacing between the frame and the fixed element. In both cases, a complex sleeve is necessary and it must be installed in the frame.
U.S. Pat. No. 1,788,481 discloses a screed jack for adjustably mounting a floor surface to a floor base. This device has a bearing surface for holding the floor surface in place, but lacks two features of the present invention. By merely using a flat piece of material as a bearing surface, there is no compensation for minor variations in the thickness of the floor covering. However, the floor covering is resting solely on top of the bearing surface, so this feature is unnecessary. There is also no way to determine if the jack is sufficiently mounted in the floor base. Both of these features are, however, important in installing wall coverings, as the weight forces act parallel to the wall surface.